The paper is concerned with the Hartian idea that the justification of law’s normativity can be traced back to the exquisite social fact, viz. special kind of social convention. After discussing the view that the rule of recognition is a coordinative convention A. Marmor’s idea of constitutive convention is introduced. Relying on J. Dickson’s brilliant enquiry I finally argue that this latter idea is deprieved of any explanatory power, which was pressuposed by H.L.A. Hart when he himself reffered to the conventional rule of recognition as social fact having full normative significance
